A sanitary washing device has conventionally been known that is installed on an upper surface of a toilet, and executes washing of, for example, a private part of a person that sits on a toilet seat. In such a sanitary washing device, a water supply pipe may be installed so as not to be exposed to an outside thereof, for example, so as to hide the water supply pipe in an internal space of a toilet (see, for example, Japanese Laid-open Patent Publication No. 2014-189999). Accordingly, a through-hole where a water supply pipe is inserted therethrough is provided on an upper surface of a toilet in order to introduce the water supply pipe into an internal space of the toilet (see, for example, Japanese Laid-open Patent Publication No. 2014-147445).
However, in a conventional sanitary washing device as described above, for example, a through-hole of a toilet may be provided at a variety of positions depending on a specification thereof, so that a water supply pipe that does not correspond to a position of a through-hole may be exposed to an outside thereof to degrade a design or appearance thereof or complicate construction thereof. That is, there is room for improvement in a conventional sanitary washing device in that a design or construction thereof is improved.